Method of rejuvenating oil and gas wells



United States Patent 3,174,929 METHOD OF REJUVENATING OIL AND GAS WELLSDonald L. Andersen, Minneapolis, Minn., assignor to 3,174,929 PatentedMar. 23, 1965 The large amounts of liquids displaced in relatively shorttimes clearly demonstrate the effectiveness of the tested compounds asfoaming agents in a variety of solution conditions.

sound, this method has not met with wide-spread acceptance because ofthe lack of foaming agents which could i be used in both oil and wateror mixed oil and water phases.

It has now been discovered that the use of compounds 1 a of the formula:

General Mills Inc a wrporafion of Delaware The foregoing examples areintended as illustrations N0 Drawing Filed Aug. 17, 1960, SenNo' 50,075of various preferred embodiments of the present inven- 1 Claim. (C1. 22- 5 tlon and are not to be construed as limitat1ons thereof. Theprocess of the present invention is highly useful The present inventionrelates to a novel method of in restoring productivity in liquid pluggedoil and gas rejuvenating oil and gas wells. More particularly, it wells.relates to the rejuvenation of oil and gas wells by add- The embodimentsof the invention in which an exing foaming agents to such wells. elusiveproperty or privilege is claimed are defined as It is well known in thepetroleum industry that the follows: accumulation 0f 9. liquid column ofwater and/or oil A process for foaming two-phase liquid mixture havinthe well shaft or bore hole of an oil or gas well may ing a liquidhydrocarbon phase and an aqueous phase render unproductive an otherwiseproductive unit. The 0 containing 0 to 10% by weight, based on the totalamount liquid column or liquid plug, as it is referred to in of Water ofan alkali metal chloride which comprises the industry, may bepetroliferous, aqueous, or a cornadding to said mixture a compound ofthe formula: bination of both. Such liquid plugs may be formed in RNHm(ACOOX)n a variety of manners, such as, ground water leak-back, formationwater build-up, crude oil accumulation, accuwhere R is an aliphatichydrocarbon group having 8 mulation of petroleum condensate'in gascondensate wells, to 22 carbon atoms, A is a divalent hydrocarbon radiora combination of one or more of the above. cal having 1 to 6 carbonatoms, X is a member selected One method suggested for removing thisliquid plug from the group consisting of hydrogen, alkali metal, and hasbeen to add a foaming agent to the well to convert amine, n is aninteger of 1 to 2 and m is an integer of the liquid column to a lighterand more easily removed 0 to 1 and the sum of m. and n is 2; passing agas into foam column. Although recognized as theoretically said mixture;and forming a foam thereby.

Table I Cone. Fluid Total 1 Foamer Active Collected Total Fluid ExampleSystem Foaming Agent n ,Foaming at20ml. Time, Collected,

. Agent, min. min. ml.

percent 1 Water only Triethanolamlnesalt o! coco fi-amlno Water 0.1 42525 440 propionic acid. 2 Kerosene only Zwitterion ofooooflaminopropionic acid. Kerosene--- 8:; "455 g8 8 3 400 kerosene, 100water Triethanolamine salt of 0000 fl-amino Water 0.5 300 38 400propionic acid. 250 kerosene, 250 water dn f? 100 kerosene, 400 water do0.1 390 490 kerosene, 10 water Zwitterion oi oleyl B-amlno propionieKerosene--. 0.5 20 340 7 400 kerosene, 100 5% NaCl-.. Ti l t ianolaminesalt 01 coco flamlno Water 0.2 350 435 propionic acid. 8 250 kerosene,250 5% NaCl... n -dn f? 5 9 490 fuel oil, 10 water lzggerion oi oleylfl-amino propionic Fuel 011..... 0.5 10 380 References Cited in the fileof this patent UNITED STATES PATENTS 2,168,116 Crites et al. Aug. 1,1939 2,619,467 Isbell Nov. 25, 1952 2,926,108 Anderson Feb. 23, 1960ment for Tired Gassers, article in the Oil and Gas Journal, vol. 57, No.6,-February 1959, pp. 108410.

Dunning et al.: Foaming Agents: Cure for Water- Logged Gas Wells,article in the Petroleum Engineer, vol. 31, November 1959, pages B28 toB33.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,174,929 March 23, 1965 Donald L. Andersen It is hereby certified that errorappears in the above numbered patent requiring correction and that thesaid Letters Patent should read as corrected below.

Column 1, line 64, after "and gas wells." insert the following:

The utilization of the method comprising the present invention isaccompanied by several unexpected advantages. For example, the compoundscontemplated for use in the present invention readily form foam in oil,water, or mixed oil-water phases, In addition, these compounds are notcorrosive and in fact inhibit the corrosion of the metallic surfaceswhich they contact.

Representative of the compounds contemplated for use in the presentinvention are the acids such as the N-alkyl-B- aminopropionic acid,N-alkyl-B-aminocrotonic acid, N-alkyl-B- amino-bis-propionic acid,N-alkyl-B-amino-bis-crotonic acid; their zwitterion forms and bothalkali metal salts and amine salts of these acids.

The above-described detergent amino acids may be prepared by a varietyof reactions. One such method comprises reacting a primary amine with alower alkyl ester of 'an unsaturated acid and then hydrolyzing the esterto the corresponding acid, as described in detail in U. S. LettersPatent 2,468,012 issued to Arthur F. Isbel on April 19, 1949. Anothermethod comprises simply reacting a primary amine with an unsaturatedacid. Still further methods are known in the art. The alkali metal andamine salts of these acids may be readily formed by conventionalmethods.

The zwitterion form of the above-described detergent amino acids may beprepared by adding to an aqueous solution of their alkali metal salts anon-oxidizing mineral acid in the manner described in detail in U. S.Letters Patent 2,816,920 issued to Donald L. Andersen on December 17,1957.

While single isolated alkylamines may be used with excellent results inpreparing these detergent amino acids by the above-described and otherreactions, the mixture of amines obtained by the amination of mixedfatty acids or selected fractions thereof present in common fats andoils are preferred because of their availability. Typical of such aminesare "coco" amine which contains fatty groups of from 8 to 18 carbonatoms and "tallow" amine which contains fatty groups of from 8 to 22carbon atoms and which are obtained by the amination of the fatty acidsor fractions thereof found in coconut oil and tallow, respectively.

The amount of foaming agent to be addedtoany given oil or gas and oilare best determined by onth espot testing procedures. Generally we find,however, that-the addition of to 2% as based on the calculated weight ofthe liquid present is adequate for most rejuvenation processes. On someoccasions it maybe desirable to use higher amounts which maybe donewithout particular disadvantage because the novel compounds used in thepresent invention are noncorosive.

In the preferred practice of the present invention the unique foamingagents are introduced into the oil or gas well bore in the form of awater or kerosene solution and agitated by use of airvor liquidpressure. In a relatively shortv period of time the foaming action issufficient to lighten the. weight of the liquid column and result in aonce more .productive well.

The present invention is further illustrated by reference to thefollowing examples. Unless otherwise indicated all parts and percentagesused herein are by weight.

Example I 9 The effectiveness of various foaming agents in therejuvenation of oil and gas wells is best determined by a simplelaboratory testg-of simulated well conditions. A .500 ml. column of testliquid containing'the appropriate foaming agent to be tested was pouredinto a vertical glass tube having a fritted glass disc near the bottomof the tube which retains the column of liquid and through which gas maybe passed. Mounted in the vertical tube 122 cm. above the fritted glassdisc is a 10 mm. O'D glass tubing overflow. The top of the vertical tubeis sealed. Dry nitrogen is passed into the tube through the fritted discatthe rate of 300 cc/min. The gas flowing through the liquid causes .afoam to form which leaves the vessel through the overflow. The amount ofliquid displaced as foam versus timeisrecorded as a measure of theeffectiveness of the foaming agent.

In testing two phase systems, an initial high gas flow is maintained inorder to obtain mixing of the phases. When the phases are sufficientlymixed, the gas flow is reduced to 300 ml/min. and timing begun. Theresults of testing preferred foaming agents under a variety ofconditions are shown in Table I Signed and sealed this 17th day ofAugust 1965.

(SEAL) Attest:

ERNEST W. SWIDER EDWARD J. BRENNER Attesting Officer Commissioner ofPatents

